The use of robotics is well established as a manufacturing expedient, particularly in applications where human handling is inefficient and/or undesirable. One such circumstance is in the semiconductor arts, in which robotics are used to handle wafers during various wafer-processing steps. Such process steps may include, by way of example, chemical mechanical planarization (CMP), etching, deposition, passivation, and various other processes in which a sealed and/or “clean” environment must be maintained, such as to limit the likelihood of contamination and to ensure that various specific processing conditions are met.
Current practice in the semiconductor arts to robotically handle these wafers often includes the use of an end effector operably attached to the robotics, such as in order to load semiconductor wafers from a loading stack into the various processing ports that may correspond to the aforementioned exemplary process steps. That is, the robotics are employed to deploy the end effector to retrieve the wafer from a particular port or stack, such as before and/or after processing in an associated process chamber. The wafer may thus be shuttled by the robotics connectively associated with the end effector to subsequent ports for additional processing. When the wafer processing stages are complete, the robotics may then return the processed semiconductor wafer to a loading port, and may, again using the end effector, then retrieve the next wafer for processing by the system. It is typical that a stack of several semiconductor wafers is processed in this manner using the end effector during each process run.
Typical end effectors hold the wafer on its bottom side, such as using backside suction provided by, for example, vacuum draw eyelets on a portion of the end effector. These vacuum eyelets are generally multiple in number and are at the distal end portion of an end effector. This distal end of the end effector may, by way of non-limiting example, have a forked shape, a spatula shape, and so on. It is these vacuum eyelets that seize each silicon wafer for robotic transfer between semi-conductor processes, wafer aligners, wafer cassettes, and so on.
In the known art, the distal portion of the end effector is typically flat with respect to the bearing arm that interfaces to the robotics and from which the distal end of the end effector extends. As such, it is typical that the vacuum eyelets that grip the silicon wafer to the end effector are of a higher height profile, such as ¼ inch in height, from the plane provided by the distal portion of the end effector. In short, this high height profile provides sufficient space between the bottom of the wafer and the distal portion of the end effector so as to avoid contact between the wafer and the end effector. Such contact is undesirable in that it may lead to wafer damage and/or contamination.
However, such high height profile vacuum eyelets typically draw very poor vacuum, and further may not provide the desired effect of precluding contact between the wafer and the end effector, at least for wafers having warped profiles. Such warping may result either from processing effects on the wafer or even be present in the pre-processed wafer. Moreover, the issue of wafer contact with the end effector may be exacerbated for large wafers in known embodiments, at least because the poor vacuum often drawn by non-conformable vacuum cups causing greater difficulty in gripping a large wafer, and this poor gripping may cause the wafer to move or drop during transport by the robot. Accordingly, there is a need for a vacuum cup for use with end effectors that provides improved vacuum and that better protects a semiconductor wafer associated with the end effector from dropping due to insufficient vacuum grip.